College textbooks are prohibitively expensive sometimes, but according to Consumer Reports, if you want the cheapest prices, Amazon tends to be the best reality for the job.

Consumer Reports looked at five different vendors, Amazon, Barnes & Noble, Bookbyte, Chegg, and Textbook Rush, as well as the price of buying the book directly from the publisher. Their results aren't particularly surprising for used books:

On average, we found that Amazon was most consistent in its low pricing, though it never had the cheapest price for any individual book. In contrast, Bookbyte and Chegg's prices were very variable. Sometimes they had the lowest prices, and sometimes their prices were very high.

With one exception, Barnes & Noble was found to be the most expensive. For example, Barnes & Noble marked "Sociology in Our Times: The Essentials," at $122.07, as compared to the cheapest price of $5.49, on Chegg.

Our test only looked at titles purchased directly from the website vendors. We did not compare prices of used books sold via the sites' marketplaces, where individuals and independent book vendors sell their wares.

Bottom line: Check out Amazon, Bookbyte or Chegg first. But make sure to view titles offered through the marketplace option offered by several of these companies; you might get lucky and find a better bargain. Prices also may change depending on the season, availability, and other factors.

So, as you'd expect, Amazon is usually the cheaper option, but it's still worth shopping around. That said, Consumer Reports didn't include shipping and taxes, so if you have Prime (which is free for students for the first six months) the books might end up being cheaper from Amazon based on shipping alone. If all else fails, our guideto saving money on textbooks should help you find the cheapest books elsewhere